1. Field of the Invention
The invention relates to the field of window dressing. More specifically, the invention provides a link system for coupling a plurality window coverings end-to-end so that they can be controlled (e.g., raised and lowered) simultaneously, the link system being adapted to allow one of the coverings to be adjusted vertically with respect to another by an angular displacement thereof.
2. Description of the Prior Art
Window treatments are conventionally installed on windows and doors to provide privacy, to form a thermal barrier against heat or cold, as well as for esthetic reasons. In some instances, for example, in some large installations most frequently required in industrial or commercial environments) since the width of a typical window covering, such as a window shade, is somewhat limited, several such coverings are arranged adjacent to each other. The conventional practice for these types of installations was to provide individual pull cords for each individual window covering. This structure is acceptable if it is desired to control the height of each window covering individually. However, it is time consuming and difficult to set all the window coverings to the same height,
Moreover, a major problem with coupled window covering such as shades is telescoping. Telescoping occurs when the window covering fabric rolls up in an uneven manner. Instead of lining up in the same horizontal position, the edges of the window covering shift either to the left or to the right. This shift may be insignificant at first, but over time, and especially for long window coverings, the shift increases significantly and eventually the covering shifts far enough to one side or the other so that it interferers with either with its own control mechanism or the control mechanism or even the actual panel of an adjacent treatment. Telescoping is especially prevalent when the window coverings are not hung horizontally.
Window coverings may not be horizontal for several reasons. While some ceilings are constructed with a nominally uniform height, many times, there are minute differences in height from one side of a room to another. This is especially true with windows or ceilings in older buildings. Over time the earth shifts, buildings settle and materials warp. These factors cause a lack of uniformity in the height of the ceiling. When standard window covering mounts are attached to the non-uniform ceiling, the problem of telescoping, as described above occurs when standard mounting hardware is used. Telescoping may also occur if two adjacent window covering segments are not properly aligned with each other.
A further problem with multiple window coverings is that even if they are coupled together, in some instances, for example, because of a slight angular offset, it is difficult to insure that the bottom of each window covering (or, more appropriately, the bottom of the window covering panel) is perfectly aligned with the adjacent window coverings (if any). However, window coverings are almost always placed at locations with very high visibility and even a slight vertical offset between adjacent window coverings is highly visible and esthetically objectionable.
Some typical coupling systems for window treatments are found in the following patents. WO 2006/042377; U.S. Pat. No. 7,051,782, EP 0863290; DE 19546203; DE 4227425; AU 200189239. However none of these references solve the problems addressed herein.